From 6f56c48384000d6cea237c837c30ab5dd437d762 Mon Sep 17 00:00:00 2001
From: Roberto Lublinerman <rluble@google.com>
Date: Thu, 9 Nov 2023 15:23:38 -0800
Subject: [PATCH] [WASM] Simplify the pass UpgradeInterfaceDispatch to avoid
 creation of stubs.

The pass was incorrectly creating abstract stubs in classes that inherited the method and luckily that was breaking invariants and aborting the compile.

The stubs do not need to be created at all.

PiperOrigin-RevId: 581041367
---
 .../passes/UpgradeInterfaceDispatch.java      | 54 ++-----------------
 1 file changed, 5 insertions(+), 49 deletions(-)

diff --git a/transpiler/java/com/google/j2cl/transpiler/passes/UpgradeInterfaceDispatch.java b/transpiler/java/com/google/j2cl/transpiler/passes/UpgradeInterfaceDispatch.java
index 28a6c8572c..46b5b2d992 100644
--- a/transpiler/java/com/google/j2cl/transpiler/passes/UpgradeInterfaceDispatch.java
+++ b/transpiler/java/com/google/j2cl/transpiler/passes/UpgradeInterfaceDispatch.java
@@ -15,24 +15,12 @@
  */
 package com.google.j2cl.transpiler.passes;
 
-import static com.google.common.collect.ImmutableSet.toImmutableSet;
-
-import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.LinkedHashMultimap;
-import com.google.common.collect.SetMultimap;
-import com.google.common.collect.Sets;
 import com.google.j2cl.transpiler.ast.AbstractRewriter;
-import com.google.j2cl.transpiler.ast.AstUtils;
 import com.google.j2cl.transpiler.ast.DeclaredTypeDescriptor;
 import com.google.j2cl.transpiler.ast.Library;
-import com.google.j2cl.transpiler.ast.Method;
 import com.google.j2cl.transpiler.ast.MethodCall;
 import com.google.j2cl.transpiler.ast.MethodDescriptor;
-import com.google.j2cl.transpiler.ast.Type;
-import com.google.j2cl.transpiler.ast.TypeDeclaration;
 import com.google.j2cl.transpiler.ast.TypeDescriptor;
-import com.google.j2cl.transpiler.ast.TypeVariable;
-import java.util.Set;
 
 /**
  * Upgrades the dispatch if the instance is not an interface type. This may happen if the type at
@@ -43,8 +31,6 @@ public final class UpgradeInterfaceDispatch extends LibraryNormalizationPass {
   @Override
   public void applyTo(Library library) {
 
-    SetMultimap<TypeDeclaration, MethodDescriptor> newMethods = LinkedHashMultimap.create();
-
     library.accept(
         new AbstractRewriter() {
           @Override
@@ -57,7 +43,7 @@ public MethodCall rewriteMethodCall(MethodCall methodCall) {
             TypeDescriptor typeDescriptor = methodCall.getQualifier().getTypeDescriptor();
 
             if (typeDescriptor.isTypeVariable()) {
-              typeDescriptor = ((TypeVariable) typeDescriptor).toRawTypeDescriptor();
+              typeDescriptor = typeDescriptor.toRawTypeDescriptor();
             }
 
             if (!typeDescriptor.isClass()) {
@@ -67,51 +53,21 @@ public MethodCall rewriteMethodCall(MethodCall methodCall) {
 
             DeclaredTypeDescriptor declaredTypeDescriptor = (DeclaredTypeDescriptor) typeDescriptor;
             MethodDescriptor newMethodDescriptor =
-                createStubMethodDescriptor(declaredTypeDescriptor, methodCall.getTarget());
-
-            newMethods.put(declaredTypeDescriptor.getTypeDeclaration(), newMethodDescriptor);
+                createNewTargetMethodDescriptor(declaredTypeDescriptor, methodCall.getTarget());
 
             return MethodCall.Builder.from(methodCall).setTarget(newMethodDescriptor).build();
           }
         });
-
-    library.streamTypes().forEach(t -> addStubMethods(t, newMethods.get(t.getDeclaration())));
   }
 
-  private static MethodDescriptor createStubMethodDescriptor(
+  /** Creates a MethodDescriptor to target a polymorphic method on a particular class. */
+  private static MethodDescriptor createNewTargetMethodDescriptor(
       DeclaredTypeDescriptor typeDescriptor, MethodDescriptor descriptor) {
     return MethodDescriptor.Builder.from(descriptor.getDeclarationDescriptor())
         .setDeclarationDescriptor(null)
         .setDefaultMethod(false)
-        .setAbstract(true)
+        .setAbstract(typeDescriptor.getTypeDeclaration().isAbstract())
         .setEnclosingTypeDescriptor(typeDescriptor.toNullable())
         .build();
   }
-
-  private static void addStubMethods(Type type, Set<MethodDescriptor> newMethodDescriptors) {
-    if (newMethodDescriptors.isEmpty()) {
-      return;
-    }
-
-    // Some interface dispatches already have targets method due to bridges that are added later.
-    ImmutableSet<String> bridgeMethodsMangledNames =
-        type.getTypeDescriptor().getPolymorphicMethods().stream()
-            .filter(m -> m.isBridge())
-            .map(MethodDescriptor::getMangledName)
-            .collect(toImmutableSet());
-
-    Set<String> existingMangledNames = Sets.newHashSet(bridgeMethodsMangledNames);
-
-    newMethodDescriptors.stream()
-        .filter(m -> existingMangledNames.add(m.getMangledName()))
-        .forEach(
-            m ->
-                type.addMember(
-                    Method.newBuilder()
-                        .setMethodDescriptor(m)
-                        .setParameters(
-                            AstUtils.createParameterVariables(m.getParameterTypeDescriptors()))
-                        .setSourcePosition(type.getSourcePosition())
-                        .build()));
-  }
 }